[Edwood]

Just out of curiosity, has anyone measured how many watts the B22 sucks out of the wall when in use?

Also wondering how many watts a balanced B22 uses. (probably pretty close to x2.)

Also, how hot does it get? We're not talking DynaHi hot, here, right?

-Ed

 

[el_matt0]

when starting up my b22, after its cooled down etc, i sometimes get VERY "unstable" dc offset readings. i believe i was registering almost 60mV on two of my boards for about 5 minutes. all the measurements seemed a bit wonky and then after about 10 minutes without touching anything, all the dc offset drops back to within 1mV of 0. how much dc offset is OK? what is dangerous, and should this initial unsteadiness be a worry? is there danger of having cans plugged in @ that point? surely this must be a common thing and not just my poor b22....

 

[amb]

el_matt0,
http://headwize.com/ubb/showpost.php...6923&pid=63445

 

[gates_2]

I've been quite stressed recently over my relay-based attenuator from dantimax.dk ... When its in the circuit, I get a noise in the background, almost like the grounding isn't fully working(read: when no pot plugged into the backpane, I get the white noise, when the stepped attenuator plugged in, it works, but the noise remains the same(varies with each step)... plug in an Alps pot... no noise..

Could it be due to the fact that the attenuator board runs on a different supply/ground from the amp?

 

[el_matt0]

Quote:

Originally Posted by amb /img/forum/go_quote.gif el_matt0, http://headwize.com/ubb/showpost.php...6923&pid=63445

thats pretty much what i figured, however is there any potential danger having the headphones plugged in? or each time i "cold" start it should i wait 15 mins before plugging in cans and turning up volume? or is it safe to just have the pot at 0 till its warmed up, with the cans in.

 

[cotdt]

I'm glad you got it working, el_matt0. And I'm glad I talked you into building this wonderful amp. See, that wasn't so hard was it?

 

[amb]

Quote:

Originally Posted by gates_2 /img/forum/go_quote.gif I've been quite stressed recently over my relay-based attenuator from dantimax.dk ... When its in the circuit, I get a noise in the background, almost like the grounding isn't fully working(read: when no pot plugged into the backpane, I get the white noise, when the stepped attenuator plugged in, it works, but the noise remains the same(varies with each step)... plug in an Alps pot... no noise.. Could it be due to the fact that the attenuator board runs on a different supply/ground from the amp?

I can't find a full schematic or documentation for your stepped attenuator on their site, but its analog "ground" must be connected to the amp's IG.

Quote:

Originally Posted by el_matt0 should i wait 15 mins before plugging in cans and turning up volume? or is it safe to just have the pot at 0 till its warmed up, with the cans in.

60mV DC offset is high, but shouldn't yet be damaging to most headphones (particularly high-Z phones). If you want peace of mind, then don't plug in headphones until the amp is warmed up, or add a ε12 muting/delay/protection circuit and set a long-ish delay time.

 

[el_matt0]

haha no it wasnt too much of a nightmare! it did take me awhile, as i had to move across country to university etc etc. i definitely had a few "bumps" along the way but it was a great learning experience and im stoked to build my next amp (a MHMAX thats sitting in front of me). man tho...it REALLY was worth it, this is an amazing sounding amp, it makes my hd650s sound like a new pair of headphones (in a good way

)! im VERY glad you talked me into it!

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif I'm glad you got it working, el_matt0. And I'm glad I talked you into building this wonderful amp. See, that wasn't so hard was it?

 

[cotdt]

Quote:

Originally Posted by el_matt0 /img/forum/go_quote.gif haha no it wasnt too much of a nightmare! it did take me awhile, as i had to move across country to university etc etc. i definitely had a few "bumps" along the way but it was a great learning experience and im stoked to build my next amp (a MHMAX thats sitting in front of me). man tho...it REALLY was worth it, this is an amazing sounding amp, it makes my hd650s sound like a new pair of headphones (in a good way )! im VERY glad you talked me into it!

Great! Now it's time to upgrade/mod your DAC!

 

[el_matt0]

i know! ive had my eyes on the benchmark..but well... $$$ lol. i know the other obvious suggestion is the opus but i dont know anything about the difficulty of that build.

 

[cotdt]

Quote:

Originally Posted by el_matt0 /img/forum/go_quote.gif i know! ive had my eyes on the benchmark..but well... $$$ lol. i know the other obvious suggestion is the opus but i dont know anything about the difficulty of that build.

LOL considering that the OPUS boards are already stuffed, and the fact that everything comes in a kit, it's far easier than the Beta22 build. 90% is just casework. Now that you accomplished the Beta22, you can feel confident about other projects (which tend to be less involved).

 

[thrice]

Quote:

Originally Posted by el_matt0 /img/forum/go_quote.gif i know! ive had my eyes on the benchmark..but well... $$$ lol. i know the other obvious suggestion is the opus but i dont know anything about the difficulty of that build.

Congrats on your build! It's the best feeling in the world when you turn on your first amp.... it works, and you start listening to it. For me that was 4 years ago with a CMOY!

Enjoy your amp!

PS...Yeah the Opus is easy, you're pretty much casing it up.

 

[el_matt0]

got a friend whose interested in putting togetehr a b22 as a speaker amp. what are going to be the upsides/merits to using 3 boards and 3 s22, vs using 2 boards and 2 s22? how important is an active ground for running bookshelf speakers? the pair he is interested in powering are Royd bookshelves. theyre pretty easy to drive, but need a "good" amp to sound up to their full potential. a b22 came to mind seeing that ive seen people build em as speaker amps and i know its possible etc etc. suggestions? at this point im kind of thinking 2 b22 boards and 2 s22 would do the trick?

 

[VncentValntine]

From what I've read, yes two boards and two PSUs (both with big heat sinks and good ventilation) is the recommended config for dedicated speaker power amp.

 

[el_matt0]

cool, thats just what i thought. cant remember if its explicitly mentioned on AMB's site, but how strong of a trafo would i want for each s22?